1. Field
This disclosure relates to a touch panel.
2. Background
Recently, a touch panel, which performs an input function through the touch to an image displayed on a display device by an input device, such as a stylus pen or a finger, has been applied to various electronic appliances. The touch panel includes a cover substrate having an active area to sense a position and an unactive area provided at a peripheral portion of the active area. A printing layer may be provided in the unactive area. The printing layer may be printed with a material representing a predetermined color so that a wire electrode and a printed circuit board to connect the wire electrode with an external circuit are not viewed from an outside.
The printing layer may be printed on the cover substrate through various schemes. In this case, the deviation in the surface roughness and the straightness of the printing layer may exert an influence on reliability. For example, in the case of the high surface roughness, when an electrode is provided on the printing layer, an electrode may be damaged by protrusions of a printing layer. In the case of the great deviation of straightness, the printing layer may be printed to an active part, so that the active area, that is, the display area may be reduced.
The printing layer is provided with a predetermined height, that is, a predetermined thickness on the cover substrate. The wire electrode, which is provided on the printing layer, and the sensing electrode, which is provided on the cover substrate, make contact with each other so that the wire electrode can be connected with the sensing electrode.
However, as the sensing electrode is connected with the wire electrode provided on the printing layer, the sensing electrode is shorted due to the step difference resulting from the height of the printing layer, so that the reliability may be deteriorated.
The sensing electrode may include a plurality of electrode parts, the electrode parts may be spaced apart from each other, and the electrode parts may be connected with each other through a bridge electrode. For example, an insulating layer may be interposed between second sensing electrodes, and a bridge electrode is formed on the insulating layer to connect the electrode parts of the sensing electrodes, which are spaced apart from each other, with each other. In this case, the alignment of the second sensing electrode, the insulating layer, and the bridge electrode may be difficult.
In this case, at least one wire may be formed to be spaced apart from the sensing electrode. A junction part is required to electrically connect the wire and the sensing electrode, which are spaced apart from each other, with each other. The junction part may be formed through a printing process. However, when the junction part is formed through the printing process, the entire surface of the substrate may be heated. Accordingly, as the entire surface of the substrate is heated, the substrate may be deformed. In particular, a material, such as polyethylene terephthalate (PET), weak against heat may have a limitation in a heating temperature.
Accordingly, the touch panel having a novel structure to solve the above problem is required.